The Rotor BSA 30 bottom bracket allows the use of a 30mm spindled Rotor 3D plus crank on a frame with an English threaded bottom bracket. So you can get the stiffness of a 30mm oversize spindle even with a threaded bottom bracket shell. The only catch is you have to use the 3D Plus crank, as the spindle on a standard BB30 crank is too short.
Like all Rotor product the precision boutique machining of these BSA 30 cups are simply beautiful. Choose your BSA 30 with ABEC5 bearings or C3 Ceramic bearings for some additional performance. Either bearings are noticeably smoother than stock outboard bearings. Rotor includes instructions and an outboard cup installation tool.